462 POULTRY CULTURE 



structure becomes more elaborate, with specialized parts, each of 

 which has a number of different qualities, the possibilities of 

 variation increase, and with the tendency to vary one of its prin- 

 cipal inherent characters, variation and specialization unchecked 

 might lead to mongrelism and to the destruction of an established 

 balance of characters, as it has in many cases in domestication. 

 Nature checks variation and extreme specialization by making the 

 creature no longer capable of independent propagation, — making 

 reproduction contingent upon the combination, at the same stage 

 of existence, of germs from two different individuals. The orderly 

 arrangement of natural processes requires that an individual shall 

 always contribute, in reproduction, an elementary germ of the same 

 character. Hence nature divides individuals, of each species re- 

 quiring this regulation, into two kinds, with differences dependent 

 upon or related to the sexual functions. A right appreciation of this 

 use of sex is of importance to all breeders of live stock, but more to 

 poultry breeders than to others, because in most kinds of poultry 

 secondary sexual characters are more marked and made more 

 important in breeding, and because in the practical work of the 

 poultry breeder the sexes are of more equal value than in horses, 

 cattle, sheep, and swine. 



Likeness in sexual reproduction. Observation of numbers of 

 offspring of the same parents shows that the parental characters 

 do not combine in the same way in all. When a sufficient number 

 of cases is considered, it is apparent that any character of either 

 parent may appear unchanged, but that in general all characters 

 blend, though not always uniformly. This lack of uniformity, 

 objectionable to the breeder because he is seeking to secure 

 uniformity, often seems to him irregular and eccentric. On the 

 contrary, it is regular, — due to individual variation and to the impos- 

 sibility of offspring being exactly like unlike parents. The likeness 

 which the breeder desires is obtained, in individuals of each gener- 

 ation, only when the parents are so nearly alike, botli in appear- 

 ance and in breeding, that the range of variation in inherited 

 characters is narrow, and, consequently, differences due to in- 

 dividual variation are slight. Briefly stated, The gcncml prob- 

 lem of the breeder is to find like aneestors.for all (or as many as 

 possible) of the individuals of a race produced in each generation. 



